MQL5: [1] Primeiro Indicador: Preço Mediano

for(int i=0; i<rates_total; i++)
  {
   ABuffer[i]=(high[i]+low[i])/2;
  }

#property indicator_chart_window
#property indicator_buffers 1
#property indicator_plots   1

#property indicator_label1  "A"
#property indicator_type1   DRAW_LINE
#property indicator_color1  clrRed
#property indicator_style1  STYLE_SOLID
#property indicator_width1  1

double         ABuffer[];

int OnInit()
  {
   SetIndexBuffer(0,ABuffer,INDICATOR_DATA);

   return(INIT_SUCCEEDED);
  }

int OnCalculate(const int rates_total,
                const int prev_calculated,
                const datetime &time[],
                const double &open[],
                const double &high[],
                const double &low[],
                const double &close[],
                const long &tick_volume[],
                const long &volume[],
                const int &spread[])
  {
   for(int i=0; i<rates_total; i++)
     {
      ABuffer[i]=(high[i]+low[i])/2;
     }

   return(rates_total);
  }
//+------------------------------------------------------------------+